Microcavities, texture symmetry, and photonic bandgaps

The dispersions of the waveguide modes of planar and wavelength-scale textured microcavities are measured and compared. We show that when just one mirror of the microcavity has a corrugated profile, the waveguide modes are dramatically altered with Bragg scattering from the texture leading to a series of flat bands and photonic band gaps. In contrast, we further show that when both mirrors possess a similar in-phase corrugation, although Bragg scattering of the modes still occurs, no bandgaps or band edges are formed. The results are explained by modeling the electric field distribution in the microcavity, and the implications of the findings for emissive devices are discussed.